Emboli protection devices and related methods of use

ABSTRACT

An evacuation sheath assembly and method of treating occluded vessels which reduces the risk of distal embolization during vascular interventions is provided. The evacuation sheath assembly includes an elongated tube defining an evacuation lumen having proximal and distal ends. A proximal sealing surface is provided on a proximal portion of the tube and is configured to form a seal with a lumen of a guided catheter. A distal sealing surface is provided on a distal portion of the tube and is configured to form a seal with a blood vessel. A method of treatment of a blood vessel using the evacuation sheath assembly includes advancing the evacuation sheath assembly into the blood vessel through a guide catheter. Prior to advancing a device across a stenosis to be treated, normal antegrade blood flow in the blood vessel proximate to the stenosis is stopped. While blood flow is stopped, the stenosis is treated. Retrograde blood flow is induced within the blood vessel to carry embolic material dislodged during treating into the evacuation sheath assembly.

DESCRIPTION OF THE INVENTION

1. Field of the Invention

The present invention relates to apparatus and methods used to preventthe introduction of emboli into the bloodstream during and after surgeryperformed to reduce or remove blockage in blood vessels.

2. Background of the Invention

Narrowing or occlusion of blood vessels, such as the walls of an artery,inhibit normal blood flow. Such blockages, whether partial or full, canhave serious medical consequences, depending upon their location withina patient's vascular system. Narrowing or blockage of the coronaryvessels that supply blood to the heart, a condition known asatherosclerosis, may cause damage to the heart. Heart attacks(myocardial infarction) may also result from this condition. Othervessels are also prone to narrowing, including carotids, renals,cerebrals, and other peripheral arteries.

Various surgical procedures are currently used to reduce or remove theblockage in blood vessels. Such procedures include balloon angioplasty,which involves inserting a balloon catheter into the narrowed oroccluded area, expanding the balloon in the narrow or occluded area, andif necessary, placing a stent in the now expanded area to keep it open.Another common procedure used is atherectomy where the lesion is cutaway and removed from the vessel, or abrasively ground, sending thesmall particulates downstream. Other endovascular procedures make use ofthrombectomy, drug delivery, radiation, stent-grafts, and variousdiagnostic devices.

Another alternative is bypass surgery in which a section of vein isremoved from, for example, the patient's leg, e.g., a saphenous vein, tobe used as a graft to form a pathway to bypass the occluded area. Thesaphenous vein graft (SVG), however, is also susceptible to becomingoccluded in a manner similar to that of the bypassed vessel. In such acase, angioplasty (with or without the use of a stent) or atherectomy isoften used on the SVG to remove or reduce the blockage.

Each of the above described procedures carries with it the risk thatsome of the treated plaque will be disrupted, resulting in embolicparticulates released in the bloodstream. These emboli, if allowed toflow through the vascular system, may cause subsequent infarctions orischemia in the patient. SVGs treated by angioplasty or atherectomycarry a particularly high risk of this result, but such problems arealso encountered in the other types of procedures mentioned, such ascarotids, or native coronary arteries, particularly those whose lesionsinclude thrombus.

Several systems to prevent emboli being released into the bloodstreamduring such procedures have been tried. One system uses a balloon tototally occlude the artery distal (downstream) to the area of blockageto be treated. In this system, a guidewire with a balloon is introducedinto the narrowed or occluded area, and passes through the narrowed oroccluded area to a position downstream of the blockage. The balloon isinflated, the blockage is reduced or removed, and then the bloodproximal to the balloon is withdrawn from the blood vessel to remove anyparticles or emboli which have resulted from the reduction of theblockage. While this system has shown a decrease in emboli relatedcomplications in patients undergoing such treatments, the event rateremains significant. One particular problem with this system is passingthe guidewire and balloon through the narrowed or occluded area prior toocclusion with the balloon, creating the risk that emboli will beproduced as the balloon passes through the blockage. Thus, anyparticulate or plaque disturbed during this passage which forms emboliprior to inflation of the balloon is free to flow through the vascularsystem, increasing the risk for infarction or ischemia. Also, any debrisor particulate matter which gathers around the edges of the balloon mayslip downstream during deflation and retrieval of the balloon. Inaddition, this system requires that blood flow be totally occluded inthe vessel for relatively prolonged intervals that may induce adversecardiac events. Although this may not be a problem clinically, manypatients perceive the occlusion of blood flow for this period of time asproblematic.

Another system used to prevent emboli being released into thebloodstream during surgical intervention is a filter. As with theocclusion balloon, the filter must pass through the narrowed or occludedarea and is deployed distal (downstream) to the blockage. The filterthen catches any particulate material generated during the removal ofthe blockage. The filter offers the benefit that blood flow is nottotally occluded. However, because the filter must pass through theblockage, it suffers from the same drawback as the previous system—riskof the creation of emboli during passage of the filter through theblockage. In addition, it is difficult to deploy the filter securelyagainst the walls of the vessel to prevent flow around the filter andany debris or particulate matter which gathers around the edges of thefilter may slip downstream during its retrieval. Also, in order to allowblood flow during the procedure, the pores of the filter should be atleast 100 microns in diameter. The majority of emboli have a diameterbetween about 40 microns and about 100 microns. Thus, the filter willnot catch the majority of emboli, which may flow downstream and cause ainfarction or ischemia. The filter also cannot prevent the passage ofcertain neurohumoral or vasoactive substances which are released intothe blood during the procedure and may contribute to generalizedvasospasm of the distal coronary tree.

Thus, there is a need for an improved system and method of treatingoccluded vessels which can reduce the risk of distal embolization duringvascular interventions. There is also a need for a system which reducesthe amount of time that total occlusion of the blood flow is necessary.

SUMMARY OF THE INVENTION

In accordance with the invention, methods and apparatuses for reducingor removing a blockage within a vessel without permitting embolizationof particulate matter are provided. The methods and apparatuses occludeblood flow for a minimal amount of time and capture particulate mattercreated during each step of the surgical process.

According to one aspect of the invention, a method of treatment of ablood vessel is provided. The method includes advancing an evacuationsheath assembly into the blood vessel, prior to advancing a deviceacross a stenosis to be treated, stopping normal antegrade blood flow inthe blood vessel proximate to the stenosis, treating the stenosis whileblood flow is stopped, and inducing retrograde blood flow within theblood vessel to carry embolic material dislodged during treating intothe evacuation sheath assembly.

According to another aspect of the invention, a method for treating adiseased blood vessel is provided. The method includes positioning aguide catheter proximate to the diseased blood vessel, positioning anevacuation sheath assembly within the diseased blood vessel, prior toadvancing a device across a diseased area of the blood vessel, stoppingnormal antegrade blood flow in the blood vessel proximate to thediseased area, advancing a guidewire through the guide catheter and theevacuation sheath assembly across the diseased area of the blood vesselwhile the blood flow is stopped, causing retrograde flow of blood withinthe diseased blood vessel to remove embolic debris dislodged byadvancement of the guidewire, advancing an interventional catheter intothe blood vessel to treat the diseased area of the blood vessel, andcausing retrograde flow of blood within the vessel to remove embolicdebris dislodged by advancement of the interventional catheter.

According to another aspect of the present invention, a method ofperforming a procedure on a blood vessel is provided. The methodincludes positioning a guide catheter proximate to the blood vessel,positioning an evacuation sheath assembly within the guide catheter,measuring pressure in the blood vessel to obtain a first pressuremeasurement, creating a seal between the evacuation sheath assembly andthe blood vessel, measuring pressure in the blood vessel to obtain asecond pressure measurement, and comparing the first and second pressuremeasurements.

According to yet another aspect of the invention, a method of isolatingfluid communication between a catheter and a blood vessel to facilitatevisualization of the blood vessel is provided. The method includesadvancing a catheter proximate to the blood vessel, advancing anevacuation sheath assembly including a sealing surface through thecatheter and partially into the blood vessel, expanding the sealingsurface to create a seal between the blood vessel and the evacuationsheath assembly thereby stopping normal blood flow in the vessel, andinjecting contrast dye into the blood vessel while the normal blood flowis stopped.

According to one aspect of the present invention, an evacuation sheathassembly is provided. The evacuation sheath assembly includes a tubehaving first and second lumens and first and second sealing surfaces,wherein the first lumen is an evacuation lumen configured to be placedin fluid communication with a bloodstream and wherein the second lumenis an inflation lumen in fluid communication with at least one of thefirst and second sealing surfaces, and a shaft in fluid communicationwith the inflation lumen and configured to connect to an inflationsource.

According to another aspect of the invention, evacuation sheath assemblyis provided. The evacuation sheath assembly includes an elongated tubedefining an expandable evacuation lumen having a compressed deliveryconfiguration and an expanded operational configuration, and a firstsealing surface configured to form a seal within a catheter and a secondsealing surface configured to form a seal with a blood vessel.

According to yet another aspect of the present invention, a combinationfor isolating fluid communication between a blood vessel and a catheteris provided. The combination includes a catheter having a lumen, and anevacuation sheath assembly configured to move within the lumen of thecatheter and having an evacuation lumen and first and second sealingsurfaces.

According to another aspect of the present invention, an evacuationsheath assembly comprises an elongated tube defining an evacuation lumenhaving proximal and distal ends, a proximal sealing surface at aproximal end of the tube configured to form a seal with a catheter, anda distal sealing surface configured to form a seal with a blood vessel.

According to a further aspect of the present invention, an evacuationsheath assembly is provided. The evacuation sheath assembly includes anelongated tube defining an evacuation lumen having open proximal anddistal ends and an inflation lumen having an open proximal end and aclosed distal end, and a first sealing region on a proximal portion ofthe evacuation lumen and a second sealing region on a distal portion ofthe evacuation lumen, wherein at least one of the first and secondsealing regions is in fluid communication with the inflation lumen, andwherein the first sealing region is expandable to a first diameter andthe second sealing region is expandable to a second diameter differentthan the first diameter.

According to another aspect of the present invention, an evacuationsheath assembly is provided and includes an elongated tube defining aninflation lumen and an expandable evacuation lumen having a compressedconfiguration and an expanded configuration, and a plurality ofexpandable surfaces along a length of the tube, wherein a most proximalexpandable surface forms a proximal sealing surface and wherein a mostdistal expandable surface forms a distal sealing surface, and whereinexpansion of the plurality of expandable surfaces expands the evacuationlumen from the compressed configuration to the expanded configuration.

According to another aspect of the present invention, an evacuationsheath assembly is provided. The evacuation sheath assembly includes anelongated sheath defining an evacuation lumen having open proximal anddistal ends, within the sheath is expandable from a deliveryconfiguration to an operational configuration, a proximal hollow shaftconnected to a proximal end of the sheath, and an actuation wireconnected to a distal end of the sheath, the actuation wire beingmovable within said shaft from a distal position to a proximal positionto expand said sheath.

According to one aspect of the present invention, a method of treatmentof a blood vessel is provided. The method includes advancing a guidecatheter proximate to the blood vessel, advancing an evacuation sheathassembly through the guide catheter and into the blood vessel whileretaining a proximal portion of the evacuation sheath assembly withinthe guide catheter, creating a first seal between the proximal portionof the evacuation sheath assembly and the guide catheter, creating asecond seal between a distal portion of the evacuation sheath assemblyand the blood vessel, stopping normal antegrade blood flow within theblood vessel, treating a stenosis within the blood vessel, causingretrograde flow within the blood vessel to thereby remove embolicmaterial dislodged during the treating and carried by the retrogradeflow into the evacuation sheath assembly, and re-establishing normalantegrade blood flow within the blood vessel.

According to another aspect of the present invention, an evacuationsheath assembly is provided. The evacuation sheath assembly includes anelongated tube defining an expandable evacuation lumen having first afirst delivery configuration and a second operational configuration, anda sealing surface on a distal portion of the evacuation lumen, thesealing surface having a non-sealing configuration that corresponds tothe first delivery configuration and a sealing configuration thatcorresponds to the second operational configuration, wherein the sealingconfiguration is configured to create a seal with a blood vessel.

According to another aspect of the present invention, an evacuationsheath assembly is provided. The evacuation sheath assembly includes anelongated tube defining an evacuation lumen having open proximal anddistal ends and an inflation lumen having an open proximal end and aclosed distal end, at least one inflatable sealing surface in fluidcommunication with the inflation lumen, and a soft steerable tip on adistal end of the elongated tube.

According to yet another aspect of the present invention, an evacuationsheath assembly includes an elongated tube defining an evacuation lumenhaving open proximal and distal ends and an inflation lumen having anopen proximal end and a closed distal end, and at least one inflatablesealing surface in fluid communication with the inflation lumen, whereinthe open distal end of the evacuation lumen is angled.

According to another aspect of the present invention, an evacuationsheath assembly is provided and includes an elongated tube defining anevacuation lumen having open proximal and distal ends and an inflationlumen having an open proximal end and a closed distal end, and first andsecond sealing surfaces on the tube, wherein the open proximal end ofthe evacuation lumen is angled.

According to a further aspect of the present invention, an evacuationsheath assembly includes an elongated tube defining an evacuation lumenhaving open proximal and distal ends and an inflation lumen having anopen proximal end and a closed distal end, and at least one inflatablesealing surface in fluid communication with the inflation lumen, whereinthe evacuation lumen is shorter than the inflation lumen.

According to another aspect of the invention, an evacuation sheathassembly is provided and includes an elongated tube defining anevacuation lumen having open proximal and distal ends and an inflationlumen having an open proximal end and a closed distal end, and at leastone inflatable sealing surface in fluid communication with the inflationlumen, wherein a proximal portion of the evacuation lumen has a firstdiameter and a distal portion of the evacuation lumen has a seconddiameter larger than the first diameter.

According to another aspect of the present invention, a method fortreating a diseased blood vessel is provided. The method includespositioning a guide catheter within the ostium of a target vessel,advancing an evacuation sheath assembly through the guide catheter andbeyond a major side branch of the target vessel, forming a first sealbetween the target vessel and a distal portion of the evacuation sheathassembly forming a second seal between the catheter and a proximalportion of the evacuation sheath assembly, and advancing aninterventional device through a lumen of the evacuation sheath assemblyto treat the target vessel.

Additional objects and advantages of the invention will be set forth inpart in the description which follows, and in part will be obvious fromthe description, or may be learned by practice of the invention. Theobjects and advantages of the invention will be realized and attained bymeans of the elements and combinations particularly pointed out in theappended claims.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory onlyand are not restrictive of the invention, as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute apart of this specification, illustrate several embodiments of theinvention and together with the description, serve to explain theprinciples of the invention. In the drawings,

FIG. 1A is a cross-sectional side view of a partial length evacuationsheath according to one embodiment of the present invention;

FIG. 1B is a cross-sectional view of the partial length evacuationsheath taken along line 1B—1B of FIG. 1A;

FIG. 1C is a cross-sectional side view of an alternative embodiment of apartial length evacuation sheath according to one embodiment of thepresent invention;

FIG. 1D is a cross-sectional view of the partial length evacuationsheath taken along line 1D—1D of FIG. 1C;

FIG. 2A is a cross-sectional side view of an expandable evacuationsheath, shown in an unexpanded state, according to another embodiment ofthe present invention;

FIG. 2B is a cross-sectional view of the unexpanded expandableevacuation sheath taken along line 2B—2B of FIG. 2A;

FIG. 2C is a cross-sectional side view of the expandable evacuationsheath of FIG. 2A in an expanded state;

FIG. 2D is a cross-sectional view of the expanded expandable evacuationsheath taken along line 2D—2D of FIG. 2C;

FIG. 2E is a cross-sectional view of the expanded evacuation sheathtaken a long line 2E—2E of FIG. 2C.

FIG. 3A is cross-sectional side view of a full-length evacuation sheathaccording to another embodiment of the present invention;.

FIG. 3B is cross-sectional view of the full-length evacuation sheathtaken along line 3B—3B of FIG. 3A;

FIG. 4A is cross-sectional side view of a guiding catheter/evacuationsheath combination according to yet another embodiment of the presentinvention;

FIG. 4B is cross-sectional view of the guiding catheter/evacuationsheath combination taken along line 4B—4B of FIG. 4A;

FIG. 5A is cross-sectional view of the partial evacuation sheath ofFIGS. 1A and 1B deployed within a vessel;

FIG. 5B is cross-sectional view of the expandable evacuation sheath ofFIGS. 2A–2D deployed within a vessel;

FIG. 5C is cross-sectional view of the full-length evacuation sheath ofFIGS. 3A and 3B deployed within a vessel;

FIG. 5D is cross-sectional view of the guiding catheter/evacuationsheath combination of FIGS. 4A and 4B deployed within a vessel;

FIGS. 6A–6I are cross-sectional views of the partial length evacuationsheath of FIGS. 1A and 1B as employed in a method according to oneaspect of the present invention;

FIGS. 7A–7I are cross-sectional views of the expandable evacuationsheath of FIGS. 2A–2D as employed in a method according to anotheraspect of the present invention;

FIGS. 8A–8I are cross-sectional views of the full-length evacuationsheath of FIGS. 3A and 3B as employed in a method according to a furtheraspect of the present invention;

FIGS. 9A–9H are cross-sectional views of the guiding catheter/evacuationsheath of FIGS. 4A and 4B as employed in a method according to yetanother aspect of the present invention;

FIG. 10A is a cross-sectional side view of another embodiment of anevacuation sheath assembly enclosed in a delivery sheath and beingdelivered through a guiding catheter;

FIG. 10B is a cross-sectional side view of a braided sheath forming anevacuation head of the evacuation sheath assembly of FIG. 10A in anunexpanded state with the delivery sheath removed;

FIG. 10C is a cross-sectional side view of the braided sheath of FIG.10B in the expanded state; and

FIG. 10D is cross-sectional view of the guiding/evacuation lumen of theevacuation sheath assembly of FIGS. 10A–10C deployed within a bloodvessel.

DESCRIPTION OF THE EMBODIMENTS

Reference will now be made in detail to the present embodiments of theinvention, examples of which are illustrated in the accompanyingdrawings. Wherever possible, the same reference numbers will be usedthroughout the drawings to refer to the same or like parts.

The present invention provides a system and method for evacuatingemboli, particulate matter, and other debris from a blood vessel, andparticularly from an occluded blood vessel. As used herein, an“occlusion,” “blockage,” or “stenosis” refers to both complete andpartial blockages of the vessels, stenoses, emboli, thrombi, plaque,debris and any other particulate matter which at least partiallyoccludes the lumen of the blood vessel.

Additionally, as used herein, “proximal” refers to the portion of theapparatus closest to the end which remains outside the patient's body,and “distal” refers to the portion closest to the end inserted into thepatient's body.

This method and apparatus are particularly suited to be used in diseasedblood vessels that have particularly fragile lesions, or vessels wherebythe consequences of even small numbers of small emboli may be clinicallysignificant. Such blood vessels include diseased SVGs, carotid arteries,coronary arteries with thrombus, and renal arteries. However, it iscontemplated that the method and apparatus can be adapted to be used inother areas, such as other blood vessels.

As embodied herein and shown in FIG. 1A, an evacuation sheath assembly100 is provided. Evacuation sheath assembly 100 includes an evacuationhead and a shaft. As embodied herein and shown in FIG. 5A, theevacuation sheath assembly 100 is sized to fit inside a guide catheterto advance a distal end of the evacuation sheath assembly into a bloodvessel to treat a stenosis.

Although described herein with respect to coronary artery intervention,it is contemplated that evacuation sheath assembly 100 may be suitablefor use in other surgical procedures in other vessels, where reductionor removal of a blockage in a blood vessel is beneficial. Additionally,although the method of use of the evacuation sheath assembly will bedescribed with respect to placing a stent within a vessel, theevacuation sheath assembly 100 can be used during other therapies, suchas angioplasty, atherectomy, thrombectomy, drug delivery, radiation, anddiagnostic procedures.

As shown in FIG. 1A, an evacuation head 132 is provided. Evacuation head132 includes a multi-lumen tube 138. The multi-lumen tube 138 ispreferably made of a relatively flexible polymer such as low-densitypolyethylene, polyurethane, or low durometer Pebax® material.Alternatively, the multi-lumen tube 138 can be made of a compositepolymer and metal material or from other suitable biocompatiblematerials exhibiting appropriate flexibility, for example. Themulti-lumen tube 138 preferably includes first and second lumens. Thefirst and preferably larger of the lumens, an evacuation lumen 140, isdesigned to allow for the passage of interventional devices such as, butnot limited to, stent delivery systems and angioplasty catheters.

The evacuation lumen 140 is also designed to allow for fluid flow, suchas blood, blood/solid mixtures, radiographic dye and saline, within theevacuation lumen 140.

This flow of fluid may occur regardless of whether an interventionaldevice is within the evacuation lumen 140. The proximal and distal ends140 a, 140 b of the evacuation lumen 140 are preferably angled to allowfor smoother passage of the evacuation sheath assembly 100 through aguide catheter, and into a blood vessel, and to facilitate smootherpassage of other therapeutic devices through the evacuation lumen 140 ofthe evacuation head 132. The larger area of the angled open ends alsoallows for larger deformable particulate matter to pass through thelumen more smoothly.

The second and preferably smaller lumen of the multi-lumen tube 138 isan inflation lumen 142 (having an open proximal end 142 a and a closeddistal end 142 b) designed to provide fluid to inflate balloons on theevacuation head 132. The fluid may be either gas or liquid in form.

An alternative construction of the multi-lumen tube 138 of theevacuation head 132 is shown in FIG. 1C. Depending on the tortuosity ofthe curves of the guide catheter and the blood vessel through which theevacuation head 132 is to be advanced, it may be desirable toincorporate a kink resisting structure. As embodied herein and shown inFIG. 1C, a coil 139 may be embedded within the multi-lumen tube 138. Acoil 139 may be positioned on the inside surface defining the evacuationlumen 140. The coil 139 can be “wound-down” initially, then re-expandedto make contact with the inner surface of evacuation lumen 140. Acovering of polyurethane can then be applied to contain the coil 139,and secure it in position within evacuation lumen 140. The polyurethanemay be applied by a solvent casting of polyurethane in an appropriatesolvent. Alternatively, the structure may be formed by coextruding theshaft tube together with a coil or braid or by other suitable means. Afurther alternative may include positioning the coil on the outersurface of the multi-lumen tube 138.

According to one aspect of the invention, the evacuation head includesat least one expandable sealing surface. As embodied herein and shown inFIG. 1A, two expandable sealing surfaces are provided. A first proximalsealing surface is configured to form a seal within the guide catheterwhich delivers the evacuation sheath assembly 100 to the surgical site,as will be described. First proximal sealing surface is preferably aproximal sealing balloon 134. A second distal sealing surface isconfigured to form a seal within the blood vessel, as also will bedescribed. Second distal sealing surface is preferably a distal sealingballoon 136. As shown in FIG. 1A, it is preferable that the distalsealing balloon 136 be larger in size than the proximal sealing balloon134. The proximal balloon 134 and the distal balloon 136 are in fluidcommunication with the inflation lumen 142 of evacuation head 132.Inflation lumen 142 is in fluid communication with a balloon inflationdevice 199 (see FIG. 5A). Although only a single inflation lumen 142 isshown, it is possible to use more than one inflation lumen. In such anembodiment, the multi-lumen tube 138 would comprise three lumens, twoinflation lumens, each one in fluid communication with one of thesealing balloons 134, 136, and one evacuation lumen. Each lumen would bein fluid communication with its own lumen extending proximally to aninflation device (not shown).

Preferably, the proximal and distal balloons 134, 136 are formed of anelastomer such as polyurethane or silicone. It is preferable to utilizeelastomeric balloons, particularly for the distal sealing balloon 136,to allow the balloon to have a range of inflated diameters, depending onthe volume of fluid infused into the balloon. Each sealing balloon 134,136 includes two waist portions, one proximal 134 a, 136 a and onedistal 134 b, 136 b of a body portion of the balloon. The waistsportions 134 a, 134 b, 136 a, 136 b are preferably secured to anexterior of the multi-lumen tube 138 using heat welding, solventbonding, or other suitable adhesive bonding techniques.

Although use of separate proximal and distal sealing balloons 134, 136is preferred, it is possible to instead use a single elastomeric tubeextending nearly the full length of the multi-lumen tube 138. The singleelastomeric tube would be secured to the outside of the multi-lumen tube138 at the distal and proximal ends 140 b, 140 a of evacuation lumen140, as well as in the middle region of the evacuation lumen 140. Inthis manner, two expandable sealing surfaces are provided by the tworegions of the single elastomeric tube which are not secured to theexterior of the shaft tube, i.e., the region between the proximal end140 a and the middle region would form a proximal sealing surface, andthe region between the distal end 140 b and the middle region would forma distal sealing surface.

As embodied herein, the balloons 134, 136 may be blow molded from tubingor dip molded to approximate the shape and minimum anticipated diameterof their final inflated condition. Particularly for the distal sealingballoon 136, further inflation would further increase the diameter, asthe balloon is preferably elastomeric. Alternatively, however, theballoons need not be pre-molded to the expanded shape. In such avariation, each balloon 134, 136 is preferably a uniform diameter tubebetween the two balloon waists 134 a, 134 b, 136 a, 136 b. As theuniform diameter tubes are preferably elastomeric materials, they can beelastically expanded to the same shape and size as the alternativepre-molded balloons. The non-pre-molded balloons would require a higherinflation pressure to expand to a particular dimension. Furthermore, thenon-pre-molded elastomeric balloons would deflate more easily, as theelasticity would help to force the inflation fluid from the interior ofthe balloons. To improve the range of expandability of the elastomericballoons, it is preferable for the body portion of each balloon 134, 136to have a length at least as great as the maximum inflated diameter, andmore preferably several times longer, for example about 3–4 timeslonger.

While it is preferred to provide the two expandable sealing surfaces oftwo elastomeric balloons 134, 136, as described above, it is possible tofabricate the proximal sealing balloon 134 of a non-elastomeric polymermolded to the shape and size as shown in FIG. 1A. Since the proximalballoon 134 is intended to be inflated within the guide catheter, it isonly necessary for the proximal balloon 134 to be inflated against theinternal diameter of the guide catheter. The distal sealing balloon 136,however, preferably has a relatively wide range of expanded diameters,and therefore benefits from being elastomeric. Additionally, if thedistal sealing balloon 136 is elastomeric, and the proximal sealingballoon 134 is fabricated of a pre-molded thin-walled polymer such asPET or nylon, and if both balloons are inflated from a common inflationlumen 142, then the proximal sealing balloon 134 will expand against theinternal surface of the guide catheter, causing a seal, prior to anysignificant expansion of the distal sealing balloon 136 beyond itsinitial dimension.

As discussed earlier, the evacuation sheath assembly 100 is configuredto be used with a guiding catheter 160 (see FIGS. 5A and 6A). Theguiding catheter 160 performs an evacuation function in combination withthe evacuation lumen 140. The guiding catheter 160 also maintains acontrast delivery function. The evacuation head 132, with its twosealing balloons 134, 136 inflated, is intended to isolate fluidcommunication of the internal lumen of the guide catheter 160 to theblood vessel 150 in which it is inserted. Preferably, proximal anddistal radiopaque markers 146 a, 146 b are placed at the site of eachballoon 134, 136. Alternatively, two markers may be placed proximallyand distally adjacent to each balloon 134, 136. The proximal and distalradiopaque markers 146 a, 146 b allow the operator to radiographicallyposition the two sealing balloons 134, 136 in the proper location withinthe guiding catheter 160 and the blood vessel 150.

In use, the distal balloon 136 is intended to be positioned distal ofthe distal tip of a guiding catheter 160 and inflated against the insidesurface of the blood vessel 150 causing a fluid tight seal between theblood vessel 150 and the balloon 136.

The proximal balloon 134 is intended to be positioned proximal of thedistal end of the guiding catheter 160 and inflated against the guidingcatheter 160 causing a fluid tight seal.

The preferred inflated diameters of the sealing balloons 134, 136 arethus determined by the intended application. For example, if theevacuation sheath assembly 100 is intended to be used in a diseasedsaphenous vein bypass graft, (SVG), a guiding catheter of 8 French maybe utilized. The proximal sealing balloon 134 will therefore require aninflated diameter capable of sealing against the inside of the guidingcatheter, typically in the range of about 0.088–0.096 inches. The distalsealing balloon 136 will need to be capable of sealing against theinside of the SVG, which typically has an inside diameter ranging fromabout 2.5–6 mm.

The length of the evacuation head 132 is dependent on the applicationfor which the evacuation sheath assembly 100 is intended to be used. Itis intended that the evacuation head 132 be long enough for the proximalsealing balloon 134 to be sealingly inflated within the guide catheter160, and the distal sealing balloon 136 to be sealingly inflated withinthe blood vessel of interest. In many applications, therefore,evacuation head 132 can be relatively short. For example, in the case ofan SVG application, this length may be on the order of 2 to 5 cm.However, in a native coronary artery application, particularly in theleft coronary circulation, it may be desired to have the evacuation head132 longer, such that the distal sealing balloon 136 is positionedbeyond the first or other main bifurcation. For example, it may bedesired to position the distal sealing balloon 136 within the leftanterior descending artery, distal of the left main artery. For thisapplication, the evacuation head 132 is preferably about 5 to about 20cm in length.

The diameter of the evacuation head 132 is also dependent on theintended application. As an example, preferred dimensions are describedhere with respect to an application in SVGs, with use of an 8 Frenchguide catheter whose inner diameter is about 0.090 inches. Theevacuation lumen 140 may be approximately 0.061 inches, which will allowthe passage of most therapeutic devices such as angioplasty catheters,stent delivery catheters, atherectomy catheters, drug deliverycatheters, etc. The inflation lumen 142 may have a dimension of about0.005 inches at the widest portion of the crescent (vertical directionin FIG. 1B). The wall thickness for most of the multi-lumen tube wall138 may be about 0.002 inches, and the balloon waist thickness may beapproximately 0.002 inches. These dimensions create an evacuation head132 having a maximum diameter (in delivery condition) of about 0.076inches, less than the inner diameter of the guide catheter 160.

According to another aspect of the invention, the evacuation sheathassembly 100 includes a shaft. As embodied herein and shown in FIG. 1A,the shaft includes a proximal shaft portion 110, an intermediate shaftportion 120, and a distal shaft portion 130 (not shown in FIG. 1A, shaftportion 130 includes evacuation head 132).

Proximal shaft portion 110 forms a hollow tube. Preferably, proximalshaft portion 110 is made of stainless steel, however, other structuresand materials, such as polymer and metallic composites, (e.g., braidreinforced polymer tubes), nickel-titanium alloy, or other suitablematerials exhibiting appropriate biocompatibility and flexibilityproperties may be used. The proximal shaft portion 110 provides fluidcommunication between an inflation apparatus (not shown) and theintermediate and distal shaft portions 120, 130. The proximal shaftportion 110 may also be coated with a polymer sleeve or spray coatingfor lubricity.

Preferably, the proximal shaft portion 110 includes markers 115 on itsexterior surface. These markers 115 are positioned to indicate to a userthat the evacuation sheath assembly 100 has been advanced through theguiding catheter 160 to a location where the distal end of theevacuation sheath assembly 100 is just proximal to the distal end of theguiding catheter 160. The proximal shaft portion 110 is preferablysecured to a luer hub 105, for example by an overlapping weld oradhesive bond joint. The luer hub 105 allows the evacuation sheathassembly 100 to be connected to an inflation apparatus for the inflationof the sealing balloons 134, 136. Any suitable inflation device may beused, including those resident in hospital cath labs.

An intermediate shaft portion 120 is secured to the proximal and distalshaft portions 110, 130, preferably by an overlapping weld or bondjoint. Intermediate shaft portion 120 forms a hollow tube. Intermediateshaft portion 120 is preferably formed of polyethylene or Pebax,however, other polymers and polymer metallic composites, such aspolyimide with an incorporated braid of stainless steel wire, or othersuitable material exhibiting appropriate biocompatibility andflexibility characteristics, may be used. The intermediate shaft portion120 provides fluid communication between the proximal shaft portion 110and the distal shaft portion 130. The intermediate shaft portion 120also transmits longitudinal force from the proximal shaft portion 110 tothe distal shaft portion 130. The intermediate shaft portion 120 ispreferably more flexible than the proximal shaft portion 110, to allownavigation of the curves within the distal region of the guidingcatheter, as are often present, particularly in cardiac relatedapplications.

A distal end of the intermediate shaft portion 120 is connected to adistal shaft portion 130, preferably by welding or bonding. Distal shaftportion 130 includes the inflation lumen 142 of multi-lumen tube 138 anda soft distal tip portion 144. As shown in FIG. 1A, the inflation lumen142 is in fluid communication with the proximal shaft portion 110 andintermediate shaft portion 120. The distal end of inflation lumen 142ends in a solid portion forming the distal end of the distal shaftportion 130. The distal end of the distal shaft portion 130 is taperedto form soft tip 144. The soft tip 144 may comprise a more flexiblepolymer secured to the distal end of the multi-lumen tube 138 of theevacuation head 132. For example, if the multi-lumen tube 138 isfabricated of high density polyethylene, the soft tip 144 may befabricated of a low durometer polyurethane or Pebax. The soft tip 144allows the evacuation sheath assembly 100 to be placed atraumaticallyinto the blood vessel, even if the blood vessel exhibits tortuosity.

The shaft of the evacuation sheath assembly preferably includes astiffness transition member 135. Stiffness transition member 135 isattached to the distal end of the proximal shaft portion 110, forexample by welding or bonding. The stiffness transition member 135 ispreferably made of stainless steel, but other metals such as nickeltitanium alloy or polymers may be used. The stiffness transition member135 is located co-axially in the inflation lumen 142 (as shown in FIG.1B) and extends from the proximal shaft portion 110 to the soft tip 144.A distal end 137 of the stiffness transition member 135 preferablyincludes a spring tip embedded into the material of the soft tip 144.Embedding the spring tip into the soft tip 144 allows the stiffnesstransition member 135 to prevent longitudinal stretching or compressingof the evacuation sheath assembly 100.

Alternatively, the distal end 137 of the stiffness transition member 135can have a enlarged welded ball or other shape which can serve tomechanically interlock the stiffness transition member 135 within thesoft tip 144. The portion of the stiffness transition member 135 withinthe tip 144 of the evacuation sheath assembly 100 also serves to allowthe tip to be formed in a “J-bend”, similar to that for coronary guidewires. The stiffness transition member 135 can then transfer rotationalforces and motion imparted from the proximal region of the evacuationsheath assembly 100 to the tip 144, to facilitate steering andnavigation of the evacuation head 132 to a desired site in the bloodvessel.

The stiffness transition member's bending stiffness decreases graduallyfrom the proximal end to the distal end of the stiffness transitionmember 135. Preferably, this is accomplished by reducing the crosssectional area of the member 135 as shown in FIG. 1A, where stiffnesstransition memberl35 includes three portions of decreasing diameter 135a, 135 b, 135 c from proximal to distal end. However, this can also beaccomplished by changes in shape and/or materials. The stiffnesstransition member 135 allows for a gradual stiffness reduction in theevacuation sheath assembly 100, which allows it to more smoothlynavigate the curves of the guiding catheter and the blood vessel. Thisshaft construction is exemplary only, and is not intended to limit theinvention.

As mentioned, although described herein with respect to stent placementin an SVG or coronary artery having a stenosis, evacuation sheathassembly 100 may be used in other surgical procedures and with othertherapeutic devices, such as balloon angioplasty, atherectomy,thrombectomy, drug delivery, radiation, and diagnostic procedures.

As embodied herein and shown in simplified drawing FIG. 6A, the lumen ofa blood vessel 150 is accessed with the distal end of a guiding catheter160, which is well known in the art and typical for coronary-typeprocedures. A coronary guide wire 170 then is advanced to a locationjust proximal to the distal tip of the guiding catheter 160. Blood flowat this point remains in the direction of normal arterial blood flow.The blood is flowing around and past the distal tip of the guidingcatheter 160 and through the stenosis 180 as indicated by arrows 190.

As shown in FIG. 6B, the evacuation sheath assembly 100 then is advancedover the guide wire 170 and positioned within the vessel 150 with thedistal radiopaque marker 146 b distal of the distal tip of the guidingcatheter 160 (i.e., within the vessel 150) and the proximal marker 146 aproximal of the distal tip of the guiding catheter 160 (i.e., withincatheter 160), as determined through appropriate imaging techniquesknown in the art. Alternatively, the guide catheter 160 may bepositioned within the ostium of the target vessel, and the evacuationsheath assembly 100 may be advanced through the catheter and beyond amajor side branch of the target vessel.

Blood flow continues to be in the direction of normal arterial bloodflow as shown by arrows 190. Because the assembly 100 has as relativelyshort evacuation head 132, the entire evacuation sheath assembly 100 canbe advanced over a conventional length coronary guide wire 170 after theguide wire 170 has been placed within the guide catheter 160.

Once the evacuation head 132 is positioned with its distal end withinthe vessel 150 while its proximal end remains in the catheter 160, thedistal and proximal sealing balloons 136, 134 are inflated as shown inFIG. 6C. The distal sealing balloon 136 provides a fluid tight sealbetween the sealing balloon 136 and the blood vessel 150 and theproximal sealing balloon 134 provides a fluid tight seal between thesealing balloon 134 and the interior diameter of the guiding catheter160. A suitable valve 184, such as a touhy borst valve, attached to theguiding catheter 160 (shown in FIG. 5A) provides a fluid tight sealagainst the guide wire 170 and the proximal shaft portion 110 of theevacuation sheath assembly 100. The three fluid tight seals establishfluid communication between the distal end of the evacuation sheathassembly 100 and a fluid collection chamber, filter, and vacuum source188, which is attached to the Y-adaptor (conventional) 184 shown in FIG.5A. A blood pressure transducer 192 is commonly connected in fluidcommunication with the lumen of the guide catheter 160 (throughadditional stop cocks or manifolds as is well-known in the art) tomonitor arterial blood pressure. As the sealing balloons 134, 136 areinflated to establish the fluid communication of the evacuation sheathassembly and guide catheter 160 with the collection chamber, filter, andvacuum source 188, the blood pressure waveform can be observed to changefrom a relatively high pressure and pulsatile waveform of the artery, toa relatively low and constant waveform of the venous pressure. Thispressure observation is an important indicator that the sealing balloons134, 136 have effectively isolated fluid communication to the coronaryartery. With the three fluid tight seals in place, a normal antegradeflow within the artery is stopped. Thus, there is substantially no bloodflow within the vessel 150, as indicated by the lack of arrows in FIG.6C.

At this point, it may be desirable to inject a small amount of contrastinto the blood vessel, via a dye injection apparatus 189 in fluidcommunication with the guide catheter 160, evacuation head 132, andblood vessel 150, to aid in navigation of the guide wire 170 across thestenosis 180. The evacuation lumen 140 of the evacuation head 132becomes an extension of the guide catheter lumen for this contrastdelivery. Because normal antegrade blood flow in the coronary artery hasbeen effectively stopped, the contrast will remain in the coronaryartery, rather than quickly washing away. This may be advantageous forthe subsequent navigation of the guide wire 170.

Once antegrade flow is stopped, as shown in FIG. 6C, the guide wire 170is advanced across the stenosis 180. In most cases, to begin advancingthe guide wire 170, the touhy borst valve 184 on the Y-adaptor (shown inFIG. 5A) will need to be opened just enough to allow for movement of thewire 170, but not so much to allow vigorous backbleeding. In theprocedure described here, it is preferred to open the valve only enoughsuch that there is little to no backbleeding, otherwise the venouspressure head in the coronary artery can cause retrograde flow duringthis step, thereby pushing all of the contrast back into the guidecatheter and out of the blood vessel.

Once the wire has crossed the stenosis 180, it may be desirable to causeretrograde flow in the coronary artery (FIG. 6D), as the act of crossinga stenosis 180 with a wire 170 (particularly a fragile lesion(stenosis), such as in an SVG) may in itself dislodge material. Anymaterial dislodged will not travel downstream, as the antegrade flow hasalready been stopped. Retrograde flow can be used to remove thedislodged material.

With all seals in place, blood flow may now be established from thedistal end of the evacuation head 132 to the collection chamber, andfilter 188 to remove any dislodged material. Retrograde flow isrepresented in FIG. 6D by arrows 195. This retrograde flow is due to thevenous pressure head, and will begin once the pressure in the collectionbottle 188 is vented to atmospheric pressure. Flow can also be increasedby applying vacuum to the collection chamber and filter 188. Thisretrograde flow will carry any dislodged material out of the patient andinto a collection chamber. The collection chamber may be a simplesyringe or may be any other suitable container. If a syringe is used,withdrawal of the plunger automatically causes a vacuum to induceretrograde flow. After enough volume has been removed, the flow can bestopped by closing the valve to atmosphere pressure or by releasing thevacuum. If desired, after any dislodged material has been removed, theballoons 134, 136 of the evacuation sheath assembly 100 may betemporarily deflated, allowing for a period of antegrade blood flow andperfusion of the vessel 150.

After any dislodged material has been removed, and after normalantegrade blood flow has been allowed, if so desired, all seals areagain established. With all seals in place, a therapeutic device such asa stent delivery system 193 is advanced across the stenosis 180 withantegrade flow stopped, as shown in FIG. 6E. The touhy borst valve 184attached to the guide catheter 160, which is shown in FIG. 5A, sealsagainst the proximal end of the therapeutic device, the guide wire 170and the proximal shaft portion 110 of the evacuation sheath assembly100. Alternatively, advancement of the delivery system may be done withretrograde flow. In a step similar to that for the guide wireadvancement, some contrast may be delivered into the vessel, allowingcontinuous visualization of the vessel and stenosis for more preciseplacement of the stent delivery catheter 193. Again, to effectively keepthe contrast in place, the touhy borst valve 184 through which the stentdelivery catheter 193 passes must be opened just enough to allow foradvancement of the device with little to no backbleeding.

Once the stent delivery system 193 is accurately positioned adjacent thestenosis 180, a stent delivery balloon is inflated to expand a stent 194against the vessel wall, opening a passage for blood flow through thestenosis 180 (FIG. 6F).

During inflation of the stent balloon, retrograde flow (if present) isdiscontinued by the occlusion of the blood vessel by the therapeuticdevice and the stoppage of any applied vacuum.

After the stent 194 is applied to the stenosis 180, the stent deliveryballoon is deflated and retrograde flow is re-established in the vessel150. Any embolic material 197 dislodged from the therapeutic site iscarried back to the evacuation lumen 140 of the evacuation head 132 bythe retrograde flow 195 (FIG. 6G). The embolic material 197 may includematerial dislodged during advancement of the therapeutic device, orduring the expansion of the stent 194, in the case where the therapeuticdevice includes a stent 194. To remove this potentially embolic debris197, the retrograde flow 195 is re-established when the therapeuticdevice is no longer occluding the blood flow, and additional vacuum ispreferably applied to the evacuation lumen 140. The therapeutic devicemay be left in place while there is retrograde flow, or it may bepositioned proximal to the stenosis 180, or even brought back within thelumen of the guide catheter 160. In some instances, once the particulate197 has been removed, additional contrast delivery to the blood vesselmay indicate a need for more therapeutic steps, e.g., further dilationof the stent with the balloon. In this case, it is more convenient tohave the balloon catheter already in position for any subsequent use.

After the embolic material is removed, the therapeutic device is removedfrom the vessel 150 (retrograde flow may or may not be maintained) (FIG.6H). The distal and proximal sealing balloons 136, 134 are then deflated(FIG. 6I), establishing normal arterial flow.

According to another aspect of the present invention, the diameter of anevacuation head may be expandable from a first introduction diameter toa second operational diameter. As embodied herein and shown in FIGS.2A–2D, an evacuation sheath assembly 200 is provided with an expandableevacuation head 232. Many of the elements present in the previousembodiment are also shown in FIGS. 2A–2D and where these elements aresubstantially the same, similar reference numerals have been used and nodetailed description of the element has been provided.

As shown in FIG. 2B, the evacuation head 232 preferably includes aninner layer 226 that will serve as an evacuation lumen and an outerlayer 228 that will serve as the sealing surfaces. Preferably, the innerlayer 226 is fabricated from polyethylene PET or Pebax, but othersuitable materials may be used. The evacuation head 232 has a proximalend 232 a and a distal end 232 b. FIGS. 2A and 2B show the evacuationhead 232 in an unexpanded state and FIGS. 2C, 2D, and 2E show theevacuation head 232 in an expanded state. The inner layer 226 of theevacuation head 232 preferably comprises a tube that unfolds to increasein diameter. In FIG. 2C, the increase in diameter assumes a step-wiseshape. Thus, preferably, a distal portion of the inner layer 226 of theevacuation head has an expanded diameter which is larger than a diameterof a guide catheter 260.

The expanded shape of the inner layer 226 of the expandable evacuationhead 232 may include a proximal portion having a first diameter and adistal portion having a second diameter, the second diameter beinglarger than the first such that the inner layer 226 of the evacuationhead 232 has a larger dimension in the region which resides within theblood vessel, as shown in FIG. 2C. Alternatively, the diameters of theproximal and distal portions of the inner layer 226 of the evacuationhead 232 may be the same, such that the diameter of an expanded innerlayer 226 is the same for the region outside of the guide catheter asthe region which resides within the guide catheter. In such anembodiment, it would be necessary to provide the distal portion of theevacuation head 232 with a larger or more expansible outer layer, i.e.,sealing surface (distal sealing balloon), to ensure a proper seal withblood vessel 250.

The distal and proximal ends of the expanded evacuation head 232 may beangled relative to its longitudinal axis, as discussed with respect tothe embodiment shown in FIG. 1A, although this is not shown in FIGS.2A–2D. The low profile folded delivery state of the evacuation head 232may not require such angles. Furthermore, if the distal end of the head232 is not angled relative to the longitudinal axis, the entire opendistal end of the expandable evacuation head 232 is suitable forpositioning close to the desired therapy site.

The outer layer 228 of evacuation head includes multiple sphericalballoons (or balloon regions) 233, including a proximal most balloon 234and a distal most balloon 236, with a cylindrical waist between eachballoon. The inner and outer layers 226, 228 of the evacuation head 232may be seam welded or bonded together around the circumference at eachwaist location, while the inner layer 226 is in its expanded condition.Prior to insertion of the evacuation sheath assembly 200 into the guidecatheter 260, the evacuation head 232 is folded into its unexpandedcondition, as shown in FIGS. 2A and 2B. When fluid, either a gas orliquid, is infused between the inner and outer layers, the outer layer228 expands radially. As the outer layer 228 expands into multipleballoon regions 233, it pulls the inner layer 226 with it, opening theevacuation lumen 240. Thus, the inner and outer layers expand togetherin the radial direction when inflated.

As discussed with respect to the embodiment shown in FIGS. 1A–1C, theevacuation head 232 comprises a multi-lumen tube 238 having anevacuation lumen 240 and an inflation lumen 242. As in the embodimentshown in FIGS. 1A–1C, the inflation lumen 242 is in fluid communicationwith intermediate and proximal shaft portions 210, 220 and is in fluidcommunication with the individual balloon segments 233, 234, 236, suchthat when fluid is infused into inflation lumen 242, the evacuation head232 expands. Further infusion of fluid into the inflation lumen of theevacuation sheath assembly will inflate the distal and proximal sealingballoons until they are appropriately sized to cause effective sealing.

As described previously, in addition to intermediate balloons 233, theevacuation head 232 includes a proximal sealing balloon 234 and a distalsealing balloon 236. The proximal sealing balloon is configured to sealwith an inner diameter of the guide catheter 260 and the distal sealingballoon is configured to seal with the inner walls of blood vessel 250.The remaining balloons 233 need only be sized to an inflated diametersufficient to “pull” open the inner layer 226 of the expandableevacuation head 232. Although three intermediate balloons 233 are shownin FIG. 2C, more or fewer balloons may be provided as appropriate, forexample depending upon the length of the evacuation head to be expanded.Although intermediate balloons 233 are intended to “pull” openevacuation lumen 240 of the evacuation head 232, balloons 233 may alsoprovide addition sealing under certain circumstances, as shown in FIG.2C. However, it is less important that the remaining balloons 233 beelastomeric, as they do not necessarily require a range of expandeddiameters.

As shown in FIGS. 2A and 2B, prior to insertion into the guide catheter260, the evacuation head 232 is folded into a reduced diameterconfiguration. As illustrated, this folding may be in a generally “w”type fold, however other folding configurations are contemplated, suchas “s” folds or “c” folds. It is also preferable to heat set the foldedevacuation head 232 in this configuration. Because the evacuation headhas been heat set in a folded configuration, once the sealing balloonsand remaining balloons are deflated after a procedure, the evacuationhead will refold toward its pre-expanded configuration.

The low profile of the evacuation head 232 in its delivery configurationand the soft tip 244 at the end of evacuation sheath assembly 200 allowthe expandable evacuation sheath assembly 200 to be passed throughsmaller and more tortuous lumens and blood vessels. The expandableevacuation lumen 240 also allows the evacuation sheath assembly 200 tobe sized more closely to the guiding catheter 260 and larger than theguiding catheter 260 in the portion that is placed distal of the guidingcatheter when it is in the expanded state. This larger lumen allows forhigh evacuation flow rates, and eases the ability for large particles tobe removed from the blood vessel during or subsequent to the therapeuticprocedure, while having a relatively small collapsed delivery condition.

In use, the evacuation sheath assembly 200 is deployed in a similarmanner as discussed with respect to evacuation sheath assembly 100. Thesteps for using evacuation sheath assembly 200 with a guide catheter 260in a vessel 250 are sequentially depicted in FIGS. 7A–7I.

As shown in FIG. 7A, guide catheter 260 and guide wire 270 are advancedproximate to a blood vessel 250. Subsequently, evacuation sheathassembly 200, with evacuation lumen 240 in its delivery configuration,is advanced over the guidewire 270 into guide catheter 260 and bloodvessel 250 (FIG. 7B). Once evacuation head 232 is properly positioned,as can be verified using proximal markers 115 and markers 246 a, 246 b,evacuation head 232 is expanded (FIG. 7C) until evacuation lumen 240 isopen. Fluid continues to be injected into the balloons until proximalballoon 234 creates a seal with the lumen of guide catheter 260 anduntil distal balloon 236 creates a seal with blood vessel 250. After theproper seals are established, the stenosis 280 is treated and anyembolic debris 297 is removed via retrograde flow 295 (FIGS. 7C–7H), aspreviously described with respect to FIGS. 6C–6H. After treatment,evacuation head 232, including proximal and distal sealing balloons 234,236, is deflated and then removed from blood vessel 250 (FIG. 7I).

According to another aspect of the present invention, the evacuationhead may comprise an elongated multi-lumen tube. As embodied herein andshown in FIGS. 3A and 3B, an evacuation sheath assembly 300 is providedwith an evacuation head 332. Many of the elements present in theprevious embodiments are also shown in FIGS. 3A and 3B and where theseelements are substantially the same, similar reference numerals havebeen used and no detailed description of the element has been provided.

As shown in FIG. 3A, evacuation head 332 includes a single elongatedmulti-lumen tube 338. The size of the tube 338 allows it to be placedthrough a guiding catheter 360 and into a blood vessel 370 (see FIG.5C). The tube may be made from a polymer such as polyethylene or Pebax®material or materials described with respect to FIG. 1A. In addition,the tube 338 may include a coil or braid, as in FIG. 1C, in all or onlyportions of the tube. The multi-lumen tube 338 includes two lumens 340,342. The larger of the lumens, the evacuation lumen 340, is designed toallow for the passage of interventional devices such as, but not limitedto stent delivery systems and angioplasty catheters. The lumen is alsodesigned to allow for fluid flow, such as blood, blood/solid mixtures,radiographic dye and saline, within the lumen as discussed with respectto FIGS. 1A–1C.

A distal end of the tube 338 is tapered into a soft tip 344, asdescribed in connection with previous embodiments. The soft tip 344allows the evacuation sheath assembly 300 to be placed more smoothlyinto the blood vessel. The tube 338 includes inflation lumen 342, whichallows for fluid communication between the proximal end of theevacuation sheath assembly 300 and an expandable sealing surface. Theelongated multi-lumen tube 338 defines the entire evacuation lumen 340,unlike the devices shown in FIGS. 1A–2D which make use of a significantlength of the lumen of the guide catheter for evacuation. For thisreason, only a single expandable sealing surface is required.

The expandable sealing surface is preferably a distal sealing balloon336. Distal sealing balloon 336 may comprise an elastomeric materialsuch as polyurethane or silicone. The distal sealing balloon 336 isconfigured be positioned distal of the distal tip of a guiding catheter360 and inflated against the blood vessel 350 causing a fluid tight sealbetween the blood vessel 350 and the balloon 336. Radiopaque marker 346is preferably placed at the site of the sealing balloon 336. Theradiopaque marker 346 allows the operator to radiographically positionthe sealing balloon 336 in the proper location within the blood vessel350. A proximal shaft portion 310 of the evacuation sheath assembly 300is sealed against a valve 384, such as a touhy borst valve, on the guidecatheter 360 creating a fluid tight seal against the evacuation sheathassembly 300 and the guiding catheter 360.

The tube 338 includes proximal markers 315 placed on the exterior of theproximal portion of the tube 338. These markers 315 are positioned toindicate that the tube 338 has been advanced through the guidingcatheter 360 to a location where the distal end of the evacuation sheathassembly 300 is just proximal to the distal end of the guiding catheter360. A proximal portion of the tube 338 is secured to a bifurcated luerhub 305 by an overlapping weld or bond joint. The bifurcated luer hub305 includes an inflation port 302 and a vacuum port 303 which allowsthe evacuation sheath assembly 300 to be connected to an inflationapparatus and a vacuum source, respectively.

In use, the evacuation sheath assembly 300 is deployed in a similarmanner to that discussed with respect to evacuation sheath assembly 100.The steps of using evacuation sheath assembly 300 with a guide catheter360 in a vessel 350 are sequentially depicted in FIGS. 8A–8I. Thedifferences between the method discussed with respect to evacuationsheath assembly 100 and that for evacuation sheath assembly 300 arediscussed below.

Because the lumen in evacuation sheath assembly 300 runs the full lengthof evacuation sheath assembly 300, the evacuation sheath assembly 300should be inserted together with the coronary guide wire 370. Also,because the lumen of the guide catheter 360 is more fully obstructed bythis evacuation sheath assembly 300, it is preferable to inject contrastdirectly into the proximal end of the evacuation lumen 340 of theevacuation sheath assembly 300 (or into both lumen 340 and the lumen ofguide catheter 360), rather than just into the lumen of the catheter360. Also, both the guide catheter lumen and the evacuation lumen 340can be used for pressure monitoring, although it is more desirable touse the evacuation lumen 340 for pressure monitoring to confirm a tightseal between the distal balloon 336 and blood vessel 350 as needed. Asopposed to the earlier discussed embodiments, only one sealing balloon336 is used to provide the seal in the evacuation sheath assembly 300,as shown in FIGS. 8C–8H.

Thus, as shown in FIG. 8A, guide catheter 360 is positioned within bloodvessel 350. Then evacuation sheath assembly 300 is advanced withguidewire 370 into blood vessel 350 (FIG. 8B). Proper positioning of adistal end of evacuation sheath assembly 300 may be confirmed usingdistal marker 346. Then distal sealing balloon 336 is inflated viainflation port 302, stopping blood flow within blood vessel 350. Ifdesired, contrast dye may be injected through evacuation lumen 340 intoblood vessel 350 to view blood vessel 350 prior to treating stenosis380. Stenosis 380 is then treated and any embolic debris 397 is removedvia retrograde flow 395 through evacuation lumen 340 (FIGS. 8C–8H), aspreviously described with respect to FIGS. 6C–6H. After treatment,distal sealing balloon 336 is deflated and evacuation sheath assembly300 is removed from blood vessel 350 (FIG. 8I).

According to another aspect of the present invention, the evacuationsheath assembly may comprise an elongated multi-lumen tube whicheliminates the need for a separate guiding catheter. As embodied hereinand shown in FIGS. 4A and 4B, an evacuation/guiding sheath assembly 400is provided with an evacuation/guiding lumen 440. Many of the elementspresent in the previous embodiments are also shown in FIGS. 4A and 4Band where these elements are substantially the same, similar referencenumerals have been used and no detailed description of the element hasbeen provided.

As shown in FIG. 4A, evacuation/guiding sheath assembly 400 includes asingle elongated multi-lumen tube 438. The size of the tube 438 allowsit to be used as a combination guiding catheter and evacuation lumen, todeliver interventional devices into a blood vessel 450. The multi-lumentube 438 is preferably formed of a Pebax®, stainless steel and Teflon®composite material, very similar to conventional guide catheters, wellknown in the art, with the exception that an additional lumen in thewall of the tube is provided. Tube 438 can be made of other suitablepolymers and metal materials. The multi-lumen tube 438 includes firstand second lumens. The larger of the lumens, the evacuation/guidinglumen 440, is designed to allow for the passage of interventionaldevices such as, but not limited to, stent delivery systems andangioplasty catheters. The lumen 440 is also designed to allow for fluidflow, such as blood, blood/solid mixtures, radiographic dye and saline,within the lumen. This flow of fluid is allowed with or without aninterventional device in the evacuation/guiding lumen 440.

The tube 438 can be pre-formed in various curvatures duringmanufacturing to allow for easy access to the ostium of severaldifferent blood vessels in a manner similar to conventional guidecatheters as known in the art. Note that FIGS. 4A and 4B do not showthese pre-formed curves. The distal end of the tube 438 is preferablyfitted with a more flexible material, forming a soft distal tip 444.This flexible tip 444 allows the evacuation/guiding lumen 440 to beplaced more smoothly into the blood vessel. The tube 438 also containsan inflation lumen 442, which allows for fluid communication between aproximal end of the evacuation/guiding sheath assembly 400 and anexpandable sealing surface on a distal end of the evacuation/guidingsheath assembly 400.

Preferably, the expandable sealing surface is an inflatable sealingballoon 436. The sealing balloon 436 is preferably elastomeric and maycomprise polyurethane or silicone, similar to that of the distal sealingballoon of FIGS. 1A–1C. The sealing balloon 436 is intended to bepositioned distal of the ostium of the blood vessel 450 and inflatedagainst the blood vessel 450 causing a fluid tight seal between theblood vessel 450 and the balloon 436. Radiopaque markers 446 arepreferably placed at the site of the sealing balloon 436 to allowradiographically verifying the position of the sealing balloon 436. Theproximal portion of the tube 438 is sealed against a interventionaldevice by a bifurcated touhy borst valve 484 attached to theevacuation/guiding sheath assembly 400 to create a fluid tight sealagainst the evacuation/guiding sheath assembly 400 and theinterventional device.

A proximal portion of the tube 338 is secured to the bifurcated touhyborst luer hub 484 by an overlapping weld or bond joint. The bifurcatedluer hub allows the evacuation sheath assembly to be connected to aninflation apparatus and a vacuum source through an inflation port 402and a vacuum port 403, respectively.

The steps of using evacuation/guiding sheath assembly 400 aresequentially depicted in simplified FIGS. 9A to 9H. Use ofevacuation/guiding sheath assembly 400 is similar to the methoddescribed with respect to evacuation sheath assembly 100. Thedifferences between the method discussed with respect to FIGS. 6A–6I andthat for evacuation/guiding sheath assembly 400 are discussed below.

The lumen of the blood vessel 450 is accessed with the distal tip 444 ofthe evacuation/guiding sheath assembly 400. A guide wire 470 is advancedto a location just proximal to the distal tip 444 of theevacuation/guiding sheath assembly 400 (FIG. 9A). Blood flow at thispoint remains in the direction of normal arterial blood flow as shown byarrows 490. The evacuation/guiding sheath assembly 400 is thenpositioned with the distal marker band 446 distal of the ostium of theblood vessel 450. Once the positioning of the distal tip 444 of theevacuation/guiding sheath assembly 400 is verified, the distal sealingballoon 436 is inflated as shown in FIG. 9B to stop normal antegradeflow. The distal sealing balloon 436 provides a fluid tight seal betweenthe sealing balloon 436 and the blood vessel 450. Alternatively, thedistal sealing balloon 436 may be shaped such that it seals against theaortal surface and the most adjacent portion of the coronary ostium (notshown).

A touhy borst valve 484 attached to the evacuation/guiding sheathassembly 400 (shown in FIG. 5D) provides a fluid tight seal around theguide wire 470.

The two fluid tight seals establish fluid communication between thedistal end of the evacuation/guiding sheath assembly 400 and a fluidcollection chamber, filter, and vacuum source 488, which is attached tothe bifurcation lumen of the touhy borst valve 484 shown in FIG. 5D, andstop normal antegrade blood flow within blood vessel 450. A bloodpressure transducer 492 is commonly connected in fluid communicationwith the lumen of the guide catheter to monitor arterial blood pressure.

If desired, contrast dye may be injected through evacuation/guidinglumen 440 into blood vessel 450 prior to treating stenosis 480. Stenosis480 is then treated and any embolic debris 497 is removed via retrogradeflow 495 through evacuation/guiding lumen 440 (FIGS. 9C–9G) aspreviously described with respect to FIGS. 6C–6H. After treatment,distal sealing balloon 436 is deflated and evacuation/guiding sheathassembly 400 is removed from blood vessel 450 (FIG. 9H).

According to another aspect of the present invention, the diameter of anevacuation head may be expandable from a first introduction diameter toa second operational diameter. As embodied herein and shown in FIGS.10A–10D, an evacuation sheath assembly 500 is provided with anexpandable evacuation head 532. Many of the elements present in theprevious embodiment are also shown in FIGS. 10A–10D and where theseelements are substantially the same, similar reference numerals havebeen used and no detailed description of the element has been provided.

The evacuation head 532 of the present embodiment is similar to thefirst and second embodiments previously discussed in that the evacuationsheath assembly 500 comprises a relatively short evacuation head 532.Evacuation sheath assembly 500 also makes use of the guide catheter 560to form a part of an evacuation lumen 540.

As shown in FIG. 10A, evacuation head 532 includes a tube 538 having asingle expandable lumen, evacuation lumen 540. Evacuation head 532 mayhave a naturally unexpanded state. Alternatively, evacuation head 532may be designed to normally be in an expanded state. However, it ispreferred to have the evacuation head 532 fabricated to have its naturalshape and size in the reduced dimension, as shown in FIG. 10B.

The evacuation head 532 includes two sealing surfaces 534, 536. Aproximal sealing surface 534 is intended to seal against an insidedistal portion of the guide catheter 560 and a distal sealing surface isintended to seal against the inside of the blood vessel 550, for examplea coronary artery or an SVG. Although it is contemplated that theexpandable evacuation head 532 could include two balloon-type seals, forexample by adding a sealing balloon to each end of a tube 538 formingevacuation head 532, it is preferable to simply allow the outer surfaceof the expandable evacuation head 532 to create the sealing surfaces534, 536.

Preferably, evacuation tube 538 is formed of a braided sheath and acoating or covering over the braided sheath. The braided sheath itselfcan be made of stainless steel (full hard or spring), Eligiloy™, nickeltitanium alloy or other metals or polymers with high elasticitycharacteristics. Preferably the braided sheath which forms tube 538 hasa length of between about 3 cm and about 20 cm.

The braided sheath can be coated with a polymer such as polyurethane,silicone and other similar elastomeric materials that can stretch andallow the braided sheath to expand. The covering or coating ispreferably a thin and flexible elastomer, which is dip coated on thebraided sheath. Since the elastomeric covering or coating is applied tothe braided sheath in its reduced dimension, the covering or coatinghelps to retain the braided sheath in its reduced dimension.

Alternatively, the braided sheath can be fitted with a fluid tight wovenmaterial that has similar expansion qualities as the braided sheath. Ifthe covering is a braided fabric, it is preferably made from polyesteror other high strength polymer yarn.

Alternatively, the covering may be formed of a spun fibers laid down inmultiple layers back and forth along the length of the braided sheath.If the fiber layers are laid down at the same helical angle as theprimary braided sheath, the covering will behave similarly to theprimary braided sheath upon expansion, requiring little or no expansileforce to expand the covering from its reduced dimension to its expandeddimension. Each fiber layer will be made of several adjacent fiberwindings to create a dense layer. Preferably, there are multiple layers,which together will be relatively impervious to fluid flow, therebyallowing sealing surfaces of the evacuation head 532 to effectivelyisolate fluid communication from the lumen of the guide catheter withthe lumen of the blood vessel.

The braided sheath is preferably fabricated at its desired reduceddiameter, for example, as utilized in an SVG with an 8 French guidecatheter, about 0.4–1.5 mm. The braided sheath is then coated or coveredat this reduced size. The braided sheath which comprises the evacuationhead 532 is preferably connected to an actuation wire 513 by a few ofthe filaments near the distal end of the braided sheath. A proximalhollow shaft 511 is connected to a few of the braid filaments near aproximal end of the evacuation head 532 and serves as an anchor point.Actuation wire 513 sits within the hollow shaft 511 and the braidedsheath is preferably bonded or welded to the proximal hollow shaft 511at the proximal end of the braided sheath and to the actuation wire 513on the distal end of the braided sheath. The bonds attach in a mannerthat does not considerably impede the free movement of the braidedsheath during expansion and contraction.

The proximal hollow shaft 511 is a tube, which preferably decreases instiffness from a proximal end to a distal end thereof. The proximalhollow shaft 511 can be made of stainless steel hypotubing,polyethylene, or a composite of polymers and metal.

Preferably, the evacuation head 532 includes a steerable spring tip 544extending from the actuation wire 513. Surrounding a portion of thespring tip 544 is a nose cone 543. The nose cone 543 serves as atapering transition between the spring tip 544 and a distal end of adelivery sheath 547. The nose cone 543 facilitates smooth advancement ofthe evacuation sheath assembly through a guide catheter 560 and into theblood vessel 550.

The delivery sheath 547 preferably comprises a tube which covers theentire length of the reduced dimension of the evacuation head 532. Thedelivery sheath 547 is connected to a wire shaft (not shown), whichemerges from a proximal end of the guide catheter 560. Duringevacuation, the delivery sheath 547 may be fully removed from the lumenof the guide catheter 560, or can be left in position within the guidecatheter 560.

If the delivery sheath 547 is intended to be removed completely from theguide catheter 560, it may include a perforated longitudinal line toallow for splitting of the delivery sheath 547 and removal of thedelivery sheath 547 from the proximal hollow shaft 511 of the evacuationsheath assembly 500.

Alternatively, if the braided sheath has an expanded natural shape andsize as shown in FIG. 10C, thereby being self-expanding upon removal ofthe delivery sheath 547, the delivery sheath 547 would preferably beusable during contracting and removal of the braided sheath. Thus, thedelivery sheath 547 could be re-advanced to cover and constrain thebraided sheath once the procedure is completed. In this manner, theevacuation sheath assembly 500 could be removed from the guide catheter560.

The proximal end of the evacuation sheath assembly 500 may have anadjustable lock to anchor the actuation wire 513 to the proximal hollowshaft 511, allowing them to be held fixed to one another. This allowsthe braided sheath to be locked into a set position.

The evacuation sheath assembly 500, in use, is depicted in FIG. 10D.

Use of evacuation sheath assembly 500 is similar to the method describedwith respect to evacuation sheath assembly 100. The differences betweenthe method discussed with respect to FIGS. 6A–6I (evacuation sheathassembly 100) and that for evacuation sheath assembly 500 are discussedbelow.

In use, a guide catheter 560 is advanced into blood vessel lumen 550over a guidewire 570. Evacuation sheath assembly 500, in a compressedstate having a reduced diameter and enclosed in delivery sheath 547, isadvanced through the lumen of guide catheter 560 over guidewire 570 andpart way into blood vessel 550. Proper positioning of a distal end ofevacuation sheath assembly 500 is confirmed using, for example, marker545, nose cone 543, or by viewing the braided sheath through imaging.

After the positioning is verified, the delivery sheath 547 is removedfrom the evacuation head 532. The actuation wire 513 is then pulledproximally while the proximal hollow shaft 511 is held stationary,preferably by a valve. Pulling the actuation wire 513 proximallylongitudinally compresses the braided sheath forming evacuation lumen540, causing it to expand in diameter. The evacuation lumen 540 expandsand the proximal sealing surface 534 of the evacuation head 532 sealsagainst the inside surface of the guide catheter 560. The portion of theevacuation lumen 540 extending beyond the guide catheter 560 and intothe blood vessel 550 continues to expand until the distal sealingsurface 536 of the evacuation head 532 seals against the inside surfaceof the blood vessel 550. Similar to previous embodiments, the expansioncan be observed with fluoroscopy, and the blood pressure can bemonitored 592 until the waveform changes from pulsatile arterialpressure to a venous pressure (again, in the example of a coronary orSVG blood vessel).

With both seals in place, normal blood flow is stopped. If desired,contrast dye may be injected through the catheter lumen into bloodvessel 550 to view blood vessel 550 prior to treating stenosis 580.Stenosis 580 is then treated and any embolic debris is removed viaretrograde flow 590 (FIG. 10D) as previously described with respect toFIGS. 6C–6H. After treatment, the actuation wire 513 is re-advanced toallow the braided sheath to contract and be maintained in its reduceddimension prior to withdrawing the evacuation sheath assembly 500 fromblood vessel 550.

Other embodiments of the invention will be apparent to those skilled inthe art from consideration of the specification and practice of theinvention disclosed herein. It is intended that the specification andexamples be considered as exemplary only, with a true scope and spiritof the invention being indicated by the following claims.

1. A method of treating a lesion within a blood vessel that supplies blood to the heart, comprising: placing a non-occluding guide catheter proximate the ostium of the blood vessel; inserting an evacuation sheath within the guide catheter, the evacuation sheath having proximal and distal ends, an evacuation lumen, and at least one sealing surface proximate the distal end, the sealing surface being configured to seal against an inner surface of the blood vessel; positioning the sealing surface within the blood vessel proximal to the lesion to be treated; inserting a dilation catheter into the evacuation sheath, the dilation catheter having a dilation balloon; advancing the dilation catheter into the blood vessel to a position where the dilation balloon is proximal to the lesion to be treated; prior to advancing the dilation balloon across the lesion to be treated, deploying the at least one sealing surface to occlude normal antegrade flow within the blood vessel adjacent to the lesion to be treated; advancing the dilation balloon across the lesion to be treated; dilating the lesion to be treated with the dilation balloon; and subsequent to dilating the lesion, using active suction to induce retrograde flow within the blood vessel.
 2. The method of claim 1, further comprising advancing a guidewire through the evacuation sheath to a position proximal to the lesion to be treated.
 3. The method of claim 2, wherein advancing the dilation catheter into the blood vessel includes advancing the dilation catheter over the guidewire.
 4. The method of claim 2, further comprising advancing the guidewire to a position distal to the lesion to be treated.
 5. The method of claim 4, wherein the guidewire is advanced to a position distal to the lesion subsequent to deploying the at least one sealing surface to occlude normal antegrade flow within the blood vessel.
 6. The method of claim 1, wherein inserting the dilation catheter includes advancing a stent into the blood vessel.
 7. The method of claim 1, wherein dilating the lesion to be treated with the dilation balloon includes positioning a stent proximate the lesion.
 8. The method of claim 1, further comprising infusing a contrast agent through the guide catheter into the blood vessel.
 9. The method of claim 8, wherein infusing the contrast agent includes infusing the contrast agent through the evacuation lumen of the evacuation sheath.
 10. The method of claim 1, wherein positioning the at least one sealing surface includes advancing the evacuation sheath beyond a major side branch of the blood vessel.
 11. The method of claim 1, wherein the non-occluding guide catheter has a substantially uniform cross-section along its length.
 12. The method of claim 1, wherein the non-occluding guide catheter does not include an occlusive device.
 13. A method of treating a lesion within a blood vessel that supplies blood to the heart, comprising: placing a guide catheter proximate the ostium of the blood vessel; inserting an evacuation sheath within the guide catheter, the evacuation sheath having proximal and distal ends, an evacuation lumen, and at least one sealing surface proximate the distal end, the sealing surface being configured to seal against an inner surface of the blood vessel; positioning the sealing surface within the blood vessel proximal to the lesion to be treated; infusing a contrast agent into the blood vessel, wherein at least a portion of the contrast agent passes through the evacuation lumen of the evacuation sheath into the blood vessel; inserting a dilation catheter into the evacuation sheath, the dilation catheter having a dilation balloon; advancing the dilation catheter into the blood vessel to a position where the dilation balloon is proximal to the lesion to be treated; prior to advancing the dilation balloon across the lesion to be treated, deploying the at least one sealing surface to occlude normal antegrade flow within the blood vessel adjacent to the lesion to be treated; advancing the dilation balloon across the lesion to be treated; dilating the lesion to be treated with the dilation balloon; and subsequent to dilating the lesion, inducing retrograde flow within the blood vessel.
 14. The method of claim 13, further comprising advancing a guidewire through the evacuation sheath to a position proximal to the lesion to be treated.
 15. The method of claim 14, wherein advancing the dilation catheter into the blood vessel includes advancing the dilation catheter over the guidewire.
 16. The method of claim 14, further comprising advancing the guidewire to a position distal to the lesion to be treated.
 17. The method of claim 16, wherein the guidewire is advanced to a position distal to the lesion subsequent to deploying the at least one sealing surface to occlude normal antegrade flow within the blood vessel.
 18. The method of claim 13, wherein inserting the dilation catheter includes advancing a stent into the blood vessel.
 19. The method of claim 13, wherein dilating the lesion to be treated with the dilation balloon includes positioning a stent proximate the lesion.
 20. The method of claim 13, further comprising removing the contrast agent from the blood vessel.
 21. The method of claim 20, wherein removing the contrast agent includes inducing retrograde flow in the blood vessel.
 22. The method of claim 13, wherein positioning the at least one sealing surface includes advancing the evacuation sheath beyond a major side branch of the blood vessel.
 23. The method of claim 13, wherein inducing retrograde flow includes applying active suction to the evacuation lumen of the evacuation sheath.
 24. The method of claim 1, wherein advancing the dilation balloon across the lesion to be treated includes advancing the dilation balloon prior to using active suction to induce retrograde flow within the blood vessel.
 25. The method of claim 5, wherein the guidewire is advanced across the lesion to be treated prior to using active suction to induce retrograde flow within the blood vessel.
 26. The method of claim 1, wherein retrograde flow is induced within the blood vessel only after dilating the lesion.
 27. The method of claim 1, wherein the evacuation sheath includes a second sealing surface proximate its proximal end, and wherein deploying the at least one sealing surface to occlude normal antegrade flow within the blood vessel includes deploying both the at least one sealing surface and the second sealing surface.
 28. The method of claim 27, wherein deploying the second sealing surface includes creating a seal between the guide catheter and the evacuation sheath.
 29. The method of claim 1, wherein advancing the dilation balloon across the lesion to be treated includes advancing the dilation balloon without active suction.
 30. The method of claim 1, further comprising advancing a guidewire across the lesion to be treated without active suction.
 31. The method of claim 13, wherein advancing the dilation balloon across the lesion to be treated includes advancing the dilation balloon prior to using active suction to induce retrograde flow within the blood vessel.
 32. The method of claim 16, wherein the guidewire is advanced to a position distal to the lesion prior to using active suction to induce retrograde flow within the blood vessel.
 33. The method of claim 13, wherein retrograde flow is induced within the blood vessel only after dilating the lesion.
 34. The method of claim 13, wherein the evacuation sheath includes a second sealing surface proximate its proximal end, and wherein deploying the at least one sealing surface to occlude normal antegrade flow within the blood vessel includes deploying both the at least one sealing surface and the second sealing surface.
 35. The method of claim 34, wherein deploying the second sealing surface includes creating a seal between the guide catheter and the evacuation sheath.
 36. The method of claim 13, wherein advancing the dilation balloon across the lesion to be treated includes advancing the dilation balloon without active suction.
 37. The method of claim 13, further comprising advancing a guidewire across the lesion to be treated without active suction.
 38. A method of treating a lesion within a blood vessel that supplies blood to the heart, comprising: placing a non-occluding guide catheter proximate the ostium of the blood vessel; inserting an evacuation sheath within the guide catheter, the evacuation sheath having proximal and distal ends, an evacuation lumen, and at least one sealing surface proximate the distal end, the sealing surface being configured to seal against an inner surface of the blood vessel; positioning the sealing surface within the blood vessel proximal to the lesion to be treated; inserting a dilation catheter into the evacuation sheath, the dilation catheter having a dilation balloon; advancing the dilation catheter into the blood vessel to a position where the dilation balloon is proximal to the lesion to be treated; prior to advancing the dilation balloon across the lesion to be treated, deploying the at least one sealing surface to occlude normal antegrade flow within the blood vessel distal to the lesion to be treated; advancing the dilation balloon across the lesion to be treated; dilating the lesion to be treated with the dilation balloon; and subsequent to dilating the lesion, using active suction to induce retrograde flow within the blood vessel.
 39. The method of claim 38, further comprising advancing a guidewire through the evacuation sheath to a position proximal to the lesion to be treated.
 40. The method of claim 38, wherein inserting the dilation catheter includes advancing a stent into the blood vessel.
 41. The method of claim 38, wherein dilating the lesion to be treated with the dilation balloon includes positioning a stent proximate the lesion.
 42. The method of claim 38, further comprising infusing a contrast agent through the guide catheter into the blood vessel.
 43. The method of claim 42, wherein infusing the contrast agent includes infusing the contrast agent through the evacuation lumen of the evacuation sheath.
 44. The method of claim 38, wherein positioning the at least one sealing surface includes advancing the evacuation sheath beyond a major side branch of the blood vessel.
 45. The method of claim 38, wherein the non-occluding guide catheter has a substantially uniform cross-section along its length.
 46. The method of claim 38, wherein the non-occluding guide catheter does not include an occlusive device.
 47. The method of claim 38, wherein advancing the dilation balloon across the lesion to be treated includes advancing the dilation balloon prior to using active suction to induce retrograde flow within the blood vessel.
 48. The method of claim 38, wherein retrograde flow is induced within the blood vessel only after dilating the lesion.
 49. The method of claim 38, wherein the evacuation sheath includes a second sealing surface proximate its proximal end, and wherein deploying the at least one sealing surface to occlude normal antegrade flow within the blood vessel includes deploying both the at least one sealing surface and the second sealing surface.
 50. The method of claim 49, wherein deploying the second sealing surface includes creating a seal between the guide catheter and the evacuation sheath.
 51. The method of claim 38, wherein advancing the dilation balloon across the lesion to be treated includes advancing the dilation balloon without active suction.
 52. The method of claim 38, further comprising advancing a guidewire across the lesion to be treated without active suction.
 53. A method of treating a lesion within a blood vessel that supplies blood to the heart, comprising: placing a guide catheter proximate the ostium of the blood vessel; inserting an evacuation sheath within the guide catheter, the evacuation sheath having proximal and distal ends, an evacuation lumen, and at least one sealing surface proximate the distal end, the sealing surface being configured to seal against an inner surface of the blood vessel; positioning the sealing surface within the blood vessel proximal to the lesion to be treated; infusing a contrast agent into the blood vessel, wherein at least a portion of the contrast agent passes through the evacuation lumen of the evacuation sheath into the blood vessel; inserting a dilation catheter into the evacuation sheath, the dilation catheter having a dilation balloon; advancing the dilation catheter into the blood vessel to a position where the dilation balloon is proximal to the lesion to be treated; prior to advancing the dilation balloon across the lesion to be treated, deploying the at least one sealing surface to occlude normal antegrade flow within the blood vessel distal to the lesion to be treated; advancing the dilation balloon across the lesion to be treated; dilating the lesion to be treated with the dilation balloon; and subsequent to dilating the lesion, inducing retrograde flow within the blood vessel.
 54. The method of claim 53, further comprising advancing a guidewire through the evacuation sheath to a position proximal to the lesion to be treated.
 55. The method of claim 53, wherein inserting the dilation catheter includes advancing a stent into the blood vessel.
 56. The method of claim 53, wherein dilating the lesion to be treated with the dilation balloon includes positioning a stent proximate the lesion.
 57. The method of claim 53, further comprising removing the contrast agent from the blood vessel.
 58. The method of claim 57, wherein removing the contrast agent includes inducing retrograde flow in the blood vessel.
 59. The method of claim 53, wherein positioning the at least one sealing surface includes advancing the evacuation sheath beyond a major side branch of the blood vessel.
 60. The method of claim 53, wherein inducing retrograde flow includes applying active suction to the evacuation lumen of the evacuation sheath.
 61. The method of claim 53, wherein advancing the dilation balloon across the lesion to be treated includes advancing the dilation balloon prior to using active suction to induce retrograde flow within the blood vessel.
 62. The method of claim 53, wherein retrograde flow is induced within the blood vessel only after dilating the lesion.
 63. The method of claim 53, wherein the evacuation sheath includes a second sealing surface proximate its proximal end, and wherein deploying the at least one sealing surface to occlude normal antegrade flow within the blood vessel includes deploying both the at least one sealing surface and the second sealing surface.
 64. The method of claim 53, wherein deploying the second sealing surface includes creating a seal between the guide catheter and the evacuation sheath.
 65. The method of claim 53, wherein advancing the dilation balloon across the lesion to be treated includes advancing the dilation balloon without active suction.
 66. The method of claim 53, further comprising advancing a guidewire across the lesion to be treated without active suction.
 67. A method of treating a lesion within a blood vessel that supplies blood to the heart, comprising: placing a non-occluding guide catheter proximate the ostium of the blood vessel; inserting an evacuation sheath within the guide catheter, the evacuation sheath having proximal and distal ends, an evacuation lumen, and at least one sealing surface proximate the distal end, the sealing surface being configured to seal against an inner surface of the blood vessel; positioning the sealing surface within the blood vessel proximal to the lesion to be treated; inserting a dilation catheter into the evacuation sheath, the dilation catheter having a dilation balloon; advancing the dilation catheter into the blood vessel to a position where the dilation balloon is proximal to the lesion to be treated; prior to advancing the dilation balloon across the lesion to be treated, deploying the at least one sealing surface to occlude normal antegrade flow within the blood vessel distal to the at least one sealing surface; advancing the dilation balloon across the lesion to be treated; dilating the lesion to be treated with the dilation balloon; and subsequent to dilating the lesion, using active suction to induce retrograde flow within the blood vessel.
 68. The method of claim 67, further comprising advancing a guidewire through the evacuation sheath to a position proximal to the lesion to be treated.
 69. The method of claim 67, wherein inserting the dilation catheter includes advancing a stent into the blood vessel.
 70. The method of claim 67, wherein dilating the lesion to be treated with the dilation balloon includes positioning a stent proximate the lesion.
 71. The method of claim 67, further comprising infusing a contrast agent through the guide catheter into the blood vessel.
 72. The method of claim 71, wherein infusing the contrast agent includes infusing the contrast agent through the evacuation lumen of the evacuation sheath.
 73. The method of claim 67, wherein positioning the at least one sealing surface includes advancing the evacuation sheath beyond a major side branch of the blood vessel.
 74. The method of claim 67, wherein the non-occluding guide catheter has a substantially uniform cross-section along its length.
 75. The method of claim 67, wherein the non-occluding guide catheter does not include an occlusive device.
 76. The method of claim 67, wherein advancing the dilation balloon across the lesion to be treated includes advancing the dilation balloon prior to using active suction to induce retrograde flow within the blood vessel.
 77. The method of claim 67, wherein retrograde flow is induced within the blood vessel only after dilating the lesion.
 78. The method of claim 67, wherein the evacuation sheath includes a second sealing surface proximate its proximal end, and wherein deploying the at least one sealing surface to occlude normal antegrade flow within the blood vessel includes deploying both the at least one sealing surface and the second sealing surface.
 79. The method of claim 78, wherein deploying the second sealing surface includes creating a seal between the guide catheter and the evacuation sheath.
 80. The method of claim 67, wherein advancing the dilation balloon across the lesion to be treated includes advancing the dilation balloon without active suction.
 81. The method of claim 67, further comprising advancing a guidewire across the lesion to be treated without active suction.
 82. A method of treating a lesion within a blood vessel that supplies blood to the heart, comprising: placing a guide catheter proximate the ostium of the blood vessel; inserting an evacuation sheath within the guide catheter, the evacuation sheath having proximal and distal ends, an evacuation lumen, and at least one sealing surface proximate the distal end, the sealing surface being configured to seal against an inner surface of the blood vessel; positioning the sealing surface within the blood vessel proximal to the lesion to be treated; infusing a contrast agent into the blood vessel, wherein at least a portion of the contrast agent passes through the evacuation lumen of the evacuation sheath into the blood vessel; inserting a dilation catheter into the evacuation sheath, the dilation catheter having a dilation balloon; advancing the dilation catheter into the blood vessel to a position where the dilation balloon is proximal to the lesion to be treated; prior to advancing the dilation balloon across the lesion to be treated, deploying the at least one sealing surface to occlude normal antegrade flow within the blood vessel distal to the at least one sealing surface; advancing the dilation balloon across the lesion to be treated; dilating the lesion to be treated with the dilation balloon; and subsequent to dilating the lesion, inducing retrograde flow within the blood vessel.
 83. The method of claim 82, further comprising advancing a guidewire through the evacuation sheath to a position proximal to the lesion to be treated.
 84. The method of claim 82, wherein inserting the dilation catheter includes advancing a stent into the blood vessel.
 85. The method of claim 82, wherein dilating the lesion to be treated with the dilation balloon includes positioning a stent proximate the lesion.
 86. The method of claim 82, further comprising removing the contrast agent from the blood vessel.
 87. The method of claim 86, wherein removing the contrast agent includes inducing retrograde flow in the blood vessel.
 88. The method of claim 82, wherein positioning the at least one sealing surface includes advancing the evacuation sheath beyond a major side branch of the blood vessel.
 89. The method of claim 82, wherein inducing retrograde flow includes applying active suction to the evacuation lumen of the evacuation sheath.
 90. The method of claim 82, wherein advancing the dilation balloon across the lesion to be treated includes advancing the dilation balloon prior to using active suction to induce retrograde flow within the blood vessel.
 91. The method of claim 82, wherein retrograde flow is induced within the blood vessel only after dilating the lesion.
 92. The method of claim 82, wherein the evacuation sheath includes a second sealing surface proximate its proximal end, and wherein deploying the at least one sealing surface to occlude normal antegrade flow within the blood vessel includes deploying both the at least one sealing surface and the second sealing surface.
 93. The method of claim 92, wherein deploying the second sealing surface includes creating a seal between the guide catheter and the evacuation sheath.
 94. The method of claim 82, wherein advancing the dilation balloon across the lesion to be treated includes advancing the dilation balloon without active suction.
 95. The method of claim 82, further comprising advancing a guidewire across the lesion to be treated without active suction.
 96. A method of treating a lesion within a blood vessel that supplies blood to the heart, comprising: placing a non-occluding guide catheter proximate the ostium of the blood vessel; inserting an evacuation sheath within the guide catheter, the evacuation sheath having proximal and distal ends, an evacuation lumen, and at least one sealing surface proximate the distal end, the sealing surface being configured to seal against an inner surface of the blood vessel; positioning the sealing surface within the blood vessel proximal to the lesion to be treated; inserting a dilation catheter into the evacuation sheath, the dilation catheter having a dilation balloon; advancing the dilation catheter into the blood vessel to a position where the dilation balloon is proximal to the lesion to be treated; prior to advancing the dilation balloon across the lesion to be treated, deploying the at least one sealing surface to occlude normal antegrade flow within the blood vessel across a cross-section of the blood vessel; advancing the dilation balloon across the lesion to be treated; dilating the lesion to be treated with the dilation balloon; and subsequent to dilating the lesion, using active suction to induce retrograde flow within the blood vessel.
 97. The method of claim 96, further comprising advancing a guidewire through the evacuation sheath to a position proximal to the lesion to be treated.
 98. The method of claim 96, wherein inserting the dilation catheter includes advancing a stent into the blood vessel.
 99. The method of claim 96, wherein dilating the lesion to be treated with the dilation balloon includes positioning a stent proximate the lesion.
 100. The method of claim 96, further comprising infusing a contrast agent through the guide catheter into the blood vessel.
 101. The method of claim 100, wherein infusing the contrast agent includes infusing the contrast agent through the evacuation lumen of the evacuation sheath.
 102. The method of claim 96, wherein positioning the at least one sealing surface includes advancing the evacuation sheath beyond a major side branch of the blood vessel.
 103. The method of claim 96, wherein the non-occluding guide catheter has a substantially uniform cross-section along its length.
 104. The method of claim 96, wherein the non-occluding guide catheter does not include an occlusive device.
 105. The method of claim 96, wherein advancing the dilation balloon across the lesion to be treated includes advancing the dilation balloon prior to using active suction to induce retrograde flow within the blood vessel.
 106. The method of claim 96, wherein retrograde flow is induced within the blood vessel only after dilating the lesion.
 107. The method of claim 96, wherein the evacuation sheath includes a second sealing surface proximate its proximal end, and wherein deploying the at least one sealing surface to occlude normal antegrade flow within the blood vessel includes deploying both the at least one sealing surface and the second sealing surface.
 108. The method of claim 107, wherein deploying the second sealing surface includes creating a seal between the guide catheter and the evacuation sheath.
 109. The method of claim 96, wherein advancing the dilation balloon across the lesion to be treated includes advancing the dilation balloon without active suction.
 110. The method of claim 96, further comprising advancing a guidewire across the lesion to be treated without active suction.
 111. A method of treating a lesion within a blood vessel that supplies blood to the heart, comprising: placing a guide catheter proximate the ostium of the blood vessel; inserting an evacuation sheath within the guide catheter, the evacuation sheath having proximal and distal ends, an evacuation lumen, and at least one sealing surface proximate the distal end, the sealing surface being configured to seal against an inner surface of the blood vessel; positioning the sealing surface within the blood vessel proximal to the lesion to be treated; infusing a contrast agent into the blood vessel, wherein at least a portion of the contrast agent passes through the evacuation lumen of the evacuation sheath into the blood vessel; inserting a dilation catheter into the evacuation sheath, the dilation catheter having a dilation balloon; advancing the dilation catheter into the blood vessel to a position where the dilation balloon is proximal to the lesion to be treated; prior to advancing the dilation balloon across the lesion to be treated, deploying the at least one sealing surface to occlude normal antegrade flow within the blood vessel across a cross-section of the blood vessel; advancing the dilation balloon across the lesion to be treated; dilating the lesion to be treated with the dilation balloon; and subsequent to dilating the lesion, inducing retrograde flow within the blood vessel.
 112. The method of claim 111, further comprising advancing a guidewire through the evacuation sheath to a position proximal to the lesion to be treated.
 113. The method of claim 111, wherein inserting the dilation catheter includes advancing a stent into the blood vessel.
 114. The method of claim 111, wherein dilating the lesion to be treated with the dilation balloon includes positioning a stent proximate the lesion.
 115. The method of claim 111, further comprising removing the contrast agent from the blood vessel.
 116. The method of claim 115, wherein removing the contrast agent includes inducing retrograde flow in the blood vessel.
 117. The method of claim 111, wherein positioning the at least one sealing surface includes advancing the evacuation sheath beyond a major side branch o the blood vessel.
 118. The method of claim 111, wherein inducing retrograde flow includes applying active suction to the evacuation lumen of the evacuation sheath.
 119. The method of claim 111, wherein advancing the dilation balloon across the lesion to be treated includes advancing the dilation balloon prior to using active suction to induce retrograde flow within the blood vessel.
 120. The method of claim 111, wherein retrograde flow is induced within the blood vessel only after dilating the lesion.
 121. The method of claim 111, wherein the evacuation sheath includes a second sealing surface proximate its proximal end, and wherein deploying the at least one sealing surface to occlude normal antegrade flow within the blood vessel includes deploying both the at least one sealing surface and the second sealing surface.
 122. The method of claim 121, wherein deploying the second sealing surface includes creating a seal between the guide catheter and the evacuation sheath.
 123. The method of claim 111, wherein advancing the dilation balloon across the lesion to be treated includes advancing the dilation balloon without active suction.
 124. The method of claim 111, further comprising advancing a guidewire across the lesion to be treated without active suction. 